1. Field of the Invention
The present invention relates to a gauge for an automobile and, more particularly, to a gauge for an automobile in which the needle thereof is brightened.
2. Description of the Related Art
Automobile gauges have hitherto been known which include needles secured to needle shafts rotatively driven in correspondence to what is measured; dials on which letters, graduations and the like are formed; light-guiding plates for introducing light to the reverse surfaces of the dials, which light illuminates the letters, the graduations and other components; and light sources. The needles themselves are brightened to enhance the ability with which the driver can see and confirm the positions of the needles at night.
Light irradiated by a light source is reflected by a reflecting face of a light-guiding plate, and is introduced to the base portion of the needle. It is reflected again by another reflecting face disposed in the base portion, and is guided into a photoconductive indicator portion of a tapered, square post-like needle. The light reaches the end of the needle while it is repeatedly reflected in the indicator portion. A layer made of a fluorescent coating material (hereinafter referred to simply as a fluorescent layer) is formed on the reverse surface of the indicator portion. The irradiated light impinging on the fluorescent layer is irregularly reflected, and the indicator portion is thereby brightened, so that the driver can see and confirm the position of the needle.
In such a conventional structure, however, since the indicator portion of the needle is shaped in the tapered, square post-like configuration, the irradiated light is likely to dissipate outside the needle as it advances toward the end of the indicator portion while it is repeatedly reflected. Thus light sufficient for illumination does not reach the end of the indicator portion, resulting in reduced illumination as the light approaches the end of the indicator portion. Furthermore, the wide area of the fluorescent layer, to which a fluorescent coating material is applied, is formed on the entire reverse surface of the indicator portion of the needle. When the irradiated light impinges on the wide area of the fluorescent layer, it is absorbed by the latter, and is lost as a result. This leads to a problem in that the indicator portion is not brightened fully.
If such a disadvantage is compensated for, a thick indicator portion must be shaped so as to introduce a large amount of light into the indicator portion, seriously limiting high-guality design options.
The present invention has been made in view of the above. The object of the invention is therefore to provide an automobile gauge equipped with a needle which has a slender configuration and a high-guality appearance. The indicator portion of the needle is uniformly brightened, and the driver can see and confirm the position of the needle.